Upcomming release 0.0.11

[sjlongland]

Hi all,

I'll probably be making a new release shortly but would appreciate some feedback before I do so. In the previous release, we gained support for TCP-connected TNCs thanks to @hemna submitting PR #7. There's also been interest in supporting serial devices on the Microsoft Windows platform as evidenced by PR #5.

Re-worked asynchronous I/O

I had a moment to have a close look at the asyncio streaming frameworks, and so have re-jigged things in the kiss-protocol branch, which should better accommodate these needs:

• KISSProtocol and KISSSubprocessProtocol have been implemented to pass the serial data received from a connection stream back to the BaseKISSDevice class. This should allow us to support many more varieties of connection in the future.
• SerialKISSDevice is now based on pyserial_asyncio. Older versions of this are still limited to POSIX platforms, but apparently newer versions do work on the Microsoft Windows platform, testing and feedback on this would be appreciated.
• TCPKISSDevice has been re-worked to use asyncio.create_connection rather than using socket directly, which again should perform better cross-platform.
• We now have SubprocKISSDevice which can pass KISS frames via stdin/stdout to a subprocess.

I've tested these on Linux, SerialKISSDevice using a NULL-modem cable to a PocketBeagle running an older aioax25-based application, and also both TCPKISSDevice and SubprocKISSDevice using socat. This seemed to be working as expected.

Python 3.4 support dropped

One downside is that with the upcoming removal of asyncio.coroutine, we have to say goodbye to Python 3.4.

I was reluctant to do this at first as it seemed I could largely avoid using coroutines in the code if I was careful about how I wrote it, but after a few attempts, I realised it was going to be a bigger burden than I wanted to carry for a hobby side project. Reviewing the minimum requirements for Python 3.5, it looks as if we don't lose many platforms: older Linux installs and Windows XP being the two notable platforms that use Python 3.4.

I was under the impression that Mac may have been affected, but it seems OS X 10.6 and later can still run the latest versions. I wasn't sure what other platforms also relied on this release… it would appear not many. Python 3.3 (which we never supported) culled a lot of legacy platforms.

Most versions of BSD are shipping recent Python versions (OpenBSD 6.9 ships with Python 3.8), and while the latest Python has dropped support for Windows 7 & 8, users of those platforms can still run Python 3.8 (which is at least getting security fixes).

Future plans

Connected-mode AX.25 is still something I wish to pursue, following that is to maybe implement Net/ROM. We can either clean-room implement it from specifications (which seem to be scarce these days), or one other option may be to port the Linux kernel's AX.25 stack to Python, since it, like aioax25, is GPLv2 licensed.

There are some long-standing bugs in the Linux kernel stack though, and so doing such a port may provide some insight as to what might be causing the bugs there with a view to fixing the kernel issues in the process.

As always, if people have ideas or feedback, feel free to share here.

[sjlongland]

If you see 0.0.11.post0, this is identical to 0.0.11, just trying to sort out a botched upload with the previous release.